System for switching over a voice call

ABSTRACT

A system and method for switching a voice call from an Instant Messaging (IM) based voice network to a cellular voice network. A telephone adapted to switch a voice call from an Instant Messaging (IM) based voice network to a cellular voice network.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/615,636 filed Dec. 22, 2006, now U.S. Pat. No. 7,778,630, issued Aug.17, 2010, the entirety of which is incorporated herein by reference

FIELD OF THE INVENTION

This invention relates generally to telecommunication, particularly to asystem and method for switching a voice call from an Instant Messaging(IM) based voice network to a cellular voice network.

BACKGROUND OF THE INVENTION

In only twenty years, mobile phones, also referred to as cellularphones, have gone from obscure and expensive gadgets to phenomenallycommon and low-cost personal commodities.

At the same time, a new mobile lifestyle enabled by mobile phones hasemerged. People use mobile phones to keep in touch with family andfriends while on-the-go. Popular features such as Short Message Service(SMS), camera and music further solidify cellular phones as must-haveitems for consumers.

With the addition of Internet access, availability of WiFi hotspots, andpopularity of Instant Messaging, a new breed of dual-mode mobile phoneshas arrived. Besides cellular telephone service, these new dual-modemobile phones can receive Instant Messaging (IM) based telephoneservices such as Yahoo! Messenger with Voice network, Google Talk,American Online (AOL) Instant Messenger Phoneline Service and Skype byconnecting to a private WiFi access point at home, or by connecting to apublic WiFi access point at a hotspot. These IM-based telephone servicesoftentimes provide alternative voice service and advanced features thatcomplement the cellular counterpart.

As these IM-based telephone services are commonly adopted by dual-modemobile phone users, a new problem surfaces: IM-based voice calls aredropped as soon as a user is out of range of a WiFi access point orhotspot. For example, in one scenario an individual lives in aneighborhood with good cellular coverage. He subscribes broadbandservice from the local cable company and has installed a WiFi accesspoint for convenience. He recently purchased a dual-mode mobile phoneand begins using Yahoo Messenger with Voice service at home. Theindividual particularly enjoys chatting with his mother in Budapestusing the IM-based voice network Yahoo Messenger with Voice in theevening while walking his dog. Unfortunately, the phone call is abruptlycut off whenever he walks beyond the coverage of his WiFi access point.The individual must make a cellular phone call to resume theconversation.

In another scenario, on a typical day before heading to work, anotherdual-mode phone user enjoys having a cup of coffee at a downtown caféthat provides hotspot Internet access. Usually, the user uses herdual-mode mobile phone to make several SKYPE phone calls over theHotspot to start the day. In one instance, the user calls a localutility company to file a complaint. After waiting 15 minutes for autility company customer service representative, and at which time theuser needs to leave for work, she is connected to a customer servicerepresentative. To her dismay, the SKYPE phone call is disconnected whenshe leaves the café and walks to her car in the parking lot.

Therefore, there is a need to provide a system and method to switch avoice call from an IM voice network to a cellular voice network.

SUMMARY OF THE INVENTION

In one aspect the present invention includes a system for switching avoice call from an IM voice network to a cellular voice networkincluding a service gateway associated with the IM-based and cellularvoice networks and logic for determining the circumstances under whichthe voice call is switched to the cellular voice network. The servicegateway is preferably adapted to receive voice calls from a call networkand create call records identifying the voice calls. In one embodimentthe call record includes an IM user identity, a call reference and acellular phone number.

In another aspect the present invention includes a wireless phoneadapted to switch an IM-based voice call to a cellular-based voice call,the phone preferably having an IM phone agent, a cellular phone agentand a switchover agent. In one embodiment the IM phone agent processesIM-based voice calls from a service gateway via an IM voice networkusing an IM user identity. Similarly, the cellular phone agent processescellular-based voice calls from a service gateway via a cellular voicenetwork using a cellular phone number. In a preferred embodiment thephone includes an audio module.

In another aspect the present invention includes a method of switchingan IM-based voice call to a cellular-based voice call in which a voicecall destined for a wireless phone is received in a service gateway, afirst call record associated with the service gateway identifying thevoice call is created, and an IM-based voice call is established over anIM voice network with an IM phone agent associated with the wirelessphone, wherein information about the IM-based voice call is included inthe first call record. The voice call destined for the wireless phone isconnected to the IM-based voice call, whereby at least a portion of thefirst call record is sent to a switchover agent associated with thewireless phone. A second call record is created which is associated withthe wireless phone wherein the second call record includes at least aportion of the first call record, and further information about theIM-based voice call. A cellular-based voice call is establishedincluding information about the cellular-based voice call in the firstcall record, the cellular-based voice call is associated with theIM-based voice call, a signal is sent to a cellular phone agentassociated with the wireless phone indicating that the cellular-basedvoice call is for switch over purpose, and the cellular-based voice callis established with the service gateway.

In one embodiment the service gateway establishes the IM-based voicecall with the IM phone agent using an IM user identity over the IM voicenetwork. In another embodiment the service gateway communicates with theIM phone agent using a protocol such Session Initiation Protocol forInstant Messaging and Presence Leveraging Extensions (SIMPLE) protocol,an Extensible Messaging and Presence Protocol (XMPP), an IM protocolbased on Open System for Communication in Realtime (OSCAR) or aproprietary protocol.

In another embodiment the wireless phone includes an audio module,whereby the IM-based voice call is connected to the audio module bysending voice signals from the IM-based voice call to the audio moduleand by sending voice signals from the audio module to the IM-based voicecall.

In another embodiment a method is provided in which the service gatewayswitches the voice call destined for the wireless phone from theIM-based voice call to the cellular-based voice call based oninformation about one or more of the IM-based and cellular-based voicecalls. In another embodiment the service gateway connects the voice calldestined for the wireless phone to the cellular-based voice call bysending voice signals from the voice call destined for the wirelessphone to the cellular-based voice call and by sending voice signals fromthe cellular-based voice call to the voice call destined for thewireless phone. In another embodiment the service gateway disconnectsthe voice call destined for the wireless phone from the IM-based voicecall by not sending voice signals from the voice call destined for thewireless phone to the IM-based voice call, and by not sending voicesignals from the IM-based voice call to the voice call destined for thewireless phone.

In another embodiment the service gateway sends a switchover commandhaving a call reference to the switchover agent. The service gateway maysend the switch over command to the switchover agent via a messagingservice such as a Short Message Service, a Multimedia Messaging Serviceor an Instant Messaging service, or via the IM-based voice call or viathe cellular-based voice call.

In yet another embodiment the switchover agent may request a user of thewireless phone whether the user wishes to switch from the IM-based voicecall to the cellular-based voice call.

In still another embodiment a method of the present invention caninclude monitoring of the voice quality of at least one of the IM-basedvoice call and the cellular-based voice call and determining whether toswitch the voice call destined for the wireless phone based onattributes of voice quality.

In another embodiment a method of the present invention may include thewireless phone establishing a cellular-based voice call to the servicegateway after establishing an IM-based voice call.

BRIEF DESCRIPTION OF DRAWINGS

For the purposes of illustrating the various aspects of the invention,there are shown in the drawings forms that are presently preferred, itbeing understood, however, that the invention is not limited to theprecise arrangements and instrumentalities shown.

FIG. 1 illustrates a system in accordance with one aspect of the presentinvention for switching a voice call from an Instant Messaging (IM)based voice network to a cellular voice network.

FIG. 2 a illustrates a process for establishing a voice call inaccordance with one aspect of the present invention.

FIG. 2 b illustrates a process for switching over a voice call inaccordance with one aspect of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following description, for the purposes of explanation, specificnumbers, materials and configurations are set forth in order to providea thorough understanding of the invention. It will be apparent, however,to a person of ordinary skill in the art, that these specific detailsare merely exemplary embodiments of the invention. In some instances,well known features may be omitted or simplified so as not to obscurethe present invention. Furthermore, reference in the specification to“one embodiment” or “an embodiment” is not meant to limit the scope ofthe invention, but instead merely provides an example of a particularfeature, structure or characteristic of the invention described inconnection with the embodiment. Insofar as various embodiments aredescribed herein, the appearances of the phase “in an embodiment” invarious places in the specification are not meant to refer to a singleor same embodiment.

With reference to the drawings, wherein like numerals indicate likeelements, there is shown in FIG. 1 in accordance with at least oneembodiment, a simplified block diagram depicting a system for switchingover a voice call from an Instant Messaging voice network to a cellularvoice network. A service gateway 180 provides to a wireless phone 110 avoice call service. As will be apparent to those having skill in theart, service gateway 180 may include any device or devices suitable toserve as a network node equipped for interfacing with another networkthat uses different protocols and as such may contain devices such asprotocol translators, impedance matching devices, rate converters, faultisolators, or signal translators as necessary to provide systeminteroperability. Service gateway 180 may comprise a protocoltranslation/mapping gateway which interconnects networks with differentnetwork protocol technologies by performing the required protocolconversions. Service gateway 180 may be a computer configured to performthe tasks of a gateway and/or a router.

In one embodiment, wireless phone 110 connects to an IM voice network134 to receive the voice call service 190 using an IM user identity 164.IM voice network 134 may be selected from any suitable Instant Messaging(IM) based voice network, such as but not limited to Yahoo! Messengerwith Voice network, Google Talk network or American Online (AOL) InstantMessenger Phoneline Service network or the like. IM voice network 134may include Skype voice network. IM user identity 164 is preferably anysuitable identifier such as but not limited to a user name, screen nameor a telephone number.

In one embodiment, wireless phone 110 connects to IM voice network 134using a WiFi network, for example, a hotspot WiFi network, a corporateWiFi network, a municipal WiFi network, or a residential WiFi network.IM voice network 134 may include the Internet and/or an Internet serviceprovider network.

In one embodiment, wireless phone 110 connects to a cellular voicenetwork 138 to receive the voice call service. Wireless phone 110receives the voice call service using a cellular phone number 168.Cellular voice network 138 includes a cellular network. Cellular voicenetwork 138 is preferably selected from among a Global System for MobileCommunications (GSM) network, a Wideband Code Division Multiple Access(W-CDMA) network, a General Packet Radio Service (GPRS) network, a CodeDivision Multiple Access One (cdmaOne) network, a CDMA2000 network, athird-generation (3G) network, a CDMA 1× Evolution-Data Optimized(1xEV-DO) network, a High-Speed Downlink Packet Access (HSDPA) network,or an Enhanced Data Rates for GSM Evolution (EDGE) network.

Service gateway 180 connects to a call network 190. Call network 190 ispreferably selected from a Public Switched Telephone network (PSTN), acellular voice network, or a corporate telephone network. In oneembodiment, call network 190 includes an IM voice network 134. Servicegateway 180 processes a voice call 195 with call network 190. Voice call195 may be selected from an IM-based voice call, such as a Yahoo!Messenger with Voice call, Google Talk voice call, American OnlineInstant Messenger Phoneline call, or Skype voice call; or a public orcorporate telephone call.

In one embodiment, service gateway 180 receives voice call 195 destinedfor wireless phone 110. Service gateway 180 establishes an IM-basedvoice call 144 to wireless phone 110 over IM voice network 134 using IMuser identity 164. Service gateway 180 connects voice call 195 to voicecall 144. After voice call 144 is established, wireless phone 110connects to voice call 195 via voice call 144.

During voice call 195, service gateway 180 establishes a cellular-basedvoice call 148 to wireless phone 110 over cellular voice network 138using cellular phone number 168. Voice call 148 is related to voice call195. Service gateway 180 connects voice call 148 to voice call 195.Wireless phone 110 switches over from voice call 144 to voice call 148.After the switch over is completed, wireless phone 110 connects to voicecall 195 via voice call 148.

Now referring to FIG. 2 a, in one embodiment a voice call is establishedwherein wireless phone 210 includes a switchover agent 219, an IM phoneagent 214 and a cellular phone agent 218. As will be apparent to onehaving ordinary skill in the art, the switchover agent 219 may be orinclude software containing suitable programming, or hardware such as aprocessor, adapted to perform the switchover agent 219 operations asdiscussed hereinbelow. Similary, IM phone agent 214 may be or include asoftware program and/or suitable processor for the processing ofIM-based voice call 244 with service gateway 280. IM phone agent 214communicates with switchover agent 219 over an Application ProgrammingInterface (API), or an inter-process communication mechanism, such as aninter-process function call. IM phone agent 214 processes IM-based voicecall 244 from service gateway 280 over IM voice network 234 using IMuser identity 264. Likewise, cellular phone agent 218 may be or includea software program and/or suitable processor for the processing ofcellular-based voice call 248 with service gateway 280. Preferablycellular phone agent 218 communicates with switchover agent 219 in asimilar fashion as IM phone agent 214. Cellular phone agent 218processes cellular-based voice call 248 from service gateway 280 overcellular voice network 238 using cellular phone number 268.

In one embodiment, service gateway 280 receives voice call 295 from callnetwork 290 destined for wireless phone 210. Service gateway 280 createsa call record 260 which includes IM user identity 264, cellular phonenumber 268, and a call reference 265 identifying voice call 295.

Service gateway 280 establishes IM-based voice call 244 with IM phoneagent 214 using IM user identity 264 over IM voice network 234. Tocommunicate with IM phone agent 214, service gateway 280 uses a protocolsuch as but not limited to Session Initiation Protocol for InstantMessaging and Presence Leveraging Extensions (SIMPLE) protocol, anExtensible Messaging and Presence Protocol (XMPP), an IM protocol basedon Open System for Communication in Realtime (OSCAR) or a proprietaryprotocol. Service gateway 280 stores information about IM-based voicecall 244 in call record 260.

Service gateway 280 connects voice call 295 to IM-based voice call 244by sending voice signals from voice call 295 to IM-based voice call 244and by sending voice signals from voice call 244 to voice call 295.

Wireless phone 210 preferably includes an audio module 217 for telephonyfunctionalities, including for example a speaker and a microphone (notshown). Wireless telephone 210 connects IM-based voice call 244 to audiomodule 217 by sending voice signals from voice call 244 to audio module217, and by sending voice signals from audio module 217 to IM-basedvoice call 244.

During the establishment of IM-based voice call 244, service gateway 280sends call reference 265 to switchover agent 219. Service gateway 280may send call reference 265 to switchover agent 219 in a variety of waysas will be apparent and understood to a skilled artisan, such as but notlimited to via IM phone agent 214 as part of the call setup procedurefor IM-based voice call 244, or in a proprietary header of a SIP INVITEmessage. In this latter embodiment IM phone agent 214 extracts callreference 265 from the SIP INVITE message and sends call reference 265to switchover agent 219. Switchover agent 219 creates call record 220.Call record 220 includes call reference 265 and information aboutIM-based voice call 244. The information about IM-based voice call 244stored in call record 220 at wireless phone 210 includes transportinformation for the IM-based voice call 244, such as a transmittingReal-time Transport Protocol/User Datagram Protocol (RTP/UDP) port and areceiving RTP/UDP port at wireless phone 210. The information is forconnecting IM-based voice call 244 to audio module 217, for example, bysending voice signals from the receiving RTP/UDP port to audio module217, and by sending voice signals from audio module 217 to thetransmitting RTP/UDP port. In one embodiment, the information includesan audio codec for IM-based voice call 244; service gateway 280processes voice signals to and from voice call 244 based on the audiocodec.

During voice call 295, service gateway 280 uses cellular phone number268 in call record 260 to establish cellular-based voice call 248 tocellular phone agent 218 over cellular voice network 238. By way ofexample, service gateway 280 uses Integrated Service Digital NetworkUser Party (ISUP) protocol to communicate with cellular voice network238, and cellular voice network 238 uses GSM Call Control (CC) protocolto communicate with cellular phone agent 218. Service gateway 280 storesinformation about voice call 248 in call record 260.

Service gateway 280 sends call reference 265 to switchover agent 219when establishing voice call 248. Service gateway 280 can send callreference 265 to switchover agent 219 in a variety of ways, such as butnot limited to via cellular phone agent 218 as part of the call setupprocedure for voice call 248 or as a calling party number. In thislatter embodiment, service gateway 280 sends call reference 265 ascalling party number in an ISUP Initial Address Message (IAM) tocellular voice network 238. In one embodiment, cellular voice network238 receives call reference 265 and sends call reference 265 as callingparty number to cellular phone agent 218 in a GSM CC SETUP message.Cellular phone agent 218 receives call reference 265 and sends callreference 265 to switchover agent 219.

Switchover agent 219 receives call reference 265. Switchover agent 219retrieves call record 220 with matching call reference 265. Switchoveragent 219 determines that voice call 248 is associated with IM-basedvoice call 244. Switchover agent 219 sends a response 215 to cellularphone agent 218, indicating that voice call 248 is for switch overpurpose. Cellular phone agent 218 receives response 215 andautomatically establishes voice call 248 with service gateway 280. Inone embodiment, switchover agent 219 does not connect voice call 248 toaudio module 217. Switchover agent 219 stores information about voicecall 248 in call record 220. The information about voice call 248 storedin call record 220 at wireless phone 210 includes transport informationfor the cellular-based voice call 248, such as a transmitting cellularchannel and a receiving cellular channel at wireless phone 210. Theinformation is for connecting voice call 248 to voice module 217, forexample, by sending voice signals from the receiving cellular channel tovoice module 217, and by sending voice signals from voice module 217 tothe transmitting cellular channel. In one embodiment, the informationincludes an audio codec for voice call 248; service gateway 280processes voice signals to and from voice call 248 based on the audiocodec.

Now referring to FIG. 2 b an embodiment of a process for switching overa voice call in accordance with one embodiment of the present inventionis shown. Service gateway 280 connects voice call 295 to IM-based voicecall 244 and is in process of switching over to cellular-based voicecall 248. A description of the switchover decision is provided infurther detail hereinbelow.

Service gateway 280 switches voice call 295 from IM-based voice call 244to voice call 248 based on information about voice calls 244 and 248 incall record 260. The information about IM-based voice call 244 stored incall record 260 at service gateway 280 includes transport informationfor the IM-based voice call 244, such as a transmitting Real-timeTransport Protocol/User Datagram Protocol (RTP/UDP) port, and areceiving RTP/UDP port at service gateway 280. The information is forconnecting IM-based voice call 244 to voice call 295, for example, bysending voice signals from the receiving RTP/UDP port to voice call 295,and by sending voice signals from voice call 295 to the transmittingRTP/UDP port. In one embodiment, the information includes an audio codecfor IM-based voice call 244; service gateway 280 processes voice signalsto and from voice call 244 based on the audio codec.

The information about voice call 248 stored in call record 260 atservice gateway 280 includes transport information for thecellular-based voice call 248, such as a line card or a digital channelat service gateway 280. The information is for connecting voice call 248to voice call 295, for example, by sending voice signals from the linecard to voice call 295, and by sending voice signals from voice call 295to the line card. In one embodiment, the information includes an audiocodec for voice call 248; service gateway 280 processes voice signals toand from voice call 248 based on the audio codec.

Service gateway 280 connects voice call 295 to cellular-based voice call248 by sending voice signals from voice call 295 to voice call 248; andby sending voice signals from voice call 248 to voice call 295. Servicegateway 280 disconnects voice call 295 from IM-based voice call 244 bynot sending voice signals from voice call 295 to IM-based voice call244; and by not sending voice signals from voice call 244 to voice call295.

In one embodiment, service gateway 280 sends a switch over command 275to switchover agent 219. Switch over command 275 includes call reference265. Service gateway 280 preferably sends switch over command 275 toswitchover agent 219 directly via a messaging service, such as a ShortMessage Service (SMS), a Multimedia Messaging Service (MMS) or anInstant Messaging (IM) service. Service gateway 280 may send switch overcommand 275 via voice call 248 or via IM-based voice call 244.

Switchover agent 219 receives switch over command 275. Switchover agent219 retrieves call record 220 that matches call reference 265 in switchover command 275. Switchover agent 219 determines to switch over fromIM-based voice call 244 to voice call 248 based on information aboutvoice calls 244 and 248 in call record 220. Switchover agent 219disconnects IM-based voice call 244 from audio module 217 by not sendingvoice signals from voice call 244 to audio module 217 and by not sendingvoice signals from audio module 217 to voice call 244. Switchover agent219 connects voice call 248 to audio module 217 by sending voice signalsfrom voice call 248 to audio module 217 and by sending voice signalsfrom audio module 217 to voice call 248.

In one embodiment, switchover agent 219 responds to service gateway 280that the switch over is completed.

A wireless phone 210 preferably includes an input module such as but notlimited to a keypad and may include a display screen. In one embodiment,after receiving switch over command 275, switchover agent 219 switchesover based on user input. Switchover agent 219 notifies user of wirelessphone 210 such as by displaying a textual or graphical representation ofthe switchover offer on the display screen, to which the user mayrespond by inputting a response using an input module on the phone 210,such as a keypad. Switchover agent 219 receives an input indicating thatthe switchover offer has been accepted by the user, and switches over.As will be apparent to those having skill in the art, a switchover offermay be an audio offer to which a user can respond verbally or using aninput module.

In one embodiment, after receiving switchover command 275, switchoveragent 219 monitors the voice quality of voice calls 244 and 248. Forexample, switchover agent 219 receives voice quality of IM-based voicecall 244 from IM phone agent 214, and voice quality of voice call 248from cellular phone agent 218. In another example, switchover agent 219receives voice quality of IM-based voice call 244 from IM voice network234 and voice quality of voice call 248 from cellular voice network 238.In yet another example, switchover agent 219 receives voice quality ofvoice calls 244 and 248 from service gateway 280. The voice quality canbe measured using an attribute indicative of radio signal strength, suchas but not limited to voice quality measured using dropped packet rate,dynamic jitter buffer depth or the like. In another embodiment,switchover agent 219 makes the decision to switch over the call based ona determination that the voice quality of voice call 248 is better thanthe voice quality of IM-based voice call 244, and switches over. In oneembodiment, switchover agent 219 determines that the voice quality ofIM-based voice call 244 is below an acceptable threshold, and switchesover.

In one embodiment, service gateway 280 may establish voice call 248based on specific criteria, such as when service gateway 280 determinesthat wireless phone 210 is under coverage of cellular voice network 238.In another embodiment, service gateway 280 establishes voice call 248when service gateway 280 determines that the voice quality of IM-basedvoice call 244 is below an acceptable threshold.

In another embodiment, after establishing IM-based voice call 244,wireless phone 210 establishes voice call 248 to service gateway 280.

In one embodiment, wireless phone 210 makes an outgoing call usingIM-based voice service. The outgoing call includes an IM-based voicecall 244 between service gateway 280 and wireless phone 210. Servicegateway 280 establishes a cellular-based voice call 248 with wirelessphone 210 so that service gateway 280 can switch over from the IM-basedvoice call 244 to the cellular-based voice call 248.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims.

1. A method of switching an Instant Messaging (IM)-based voice call to acellular-based voice call comprising the steps of: receiving in aservice gateway a voice call destined for a telephone number, creating afirst call record associated with the service gateway identifying thevoice call, establishing over an IM voice network an IM-based voice callwith an IM phone agent, including in the first call record firstinformation about the IM-based voice call, connecting the voice call tothe IM-based voice call, sending at least a portion of the first callrecord to a switchover agent, creating a second call record associatedwith the telephone number including the at least a portion of the firstcall record and second information about the IM-based voice call,establishing a cellular-based voice call and including information aboutthe cellular-based voice call in the first call record, associating thecellular-based voice call with the IM-based voice call, sending a signalto a cellular phone agent indicating that the cellular-based voice callis for switch over purpose, and establishing the cellular-based voicecall with the service gateway.
 2. The method according to claim 1wherein the telephone number is associated with a wireless phone.
 3. Themethod according to claim 1 wherein the service gateway switches thevoice call destined for the telephone number from the IM-based voicecall to the cellular-based voice call.
 4. The method according to claim3 wherein the switchover is based on information about the IM-basedvoice call and the cellular-based voice call.
 5. The method according toclaim 4 wherein the switchover is based on whether the quality of thecellular voice call is better than IM-based voice call.
 6. The methodaccording to claim 4 wherein the switchover is based on whether thequality of the IM-based voice call is below an acceptable threshold. 7.The method according to claim 1 wherein the switchover is based on auser accepting a switchover offer from the switchover agent.
 8. Themethod according to claim 1 comprising establishing the cellular-basedvoice call using a cellular telephone number wherein the cellulartelephone number is different from the telephone number.
 9. The methodaccording to claim 1 comprising establishing the IM-based voice callusing a IM user identity wherein the IM user identity is different fromthe telephone number.
 10. A system for switching a voice call from anInstant Messaging (IM) voice network to a cellular voice networkcomprising a service gateway associated with at least one IM-basednetwork, at least one cellular voice network, and a switchover agent,the service gateway comprising a computer readable medium with softwarestored thereon and a processor configured to receive at least one voicecall destined for a telephone number from a call network and create atleast one call record associated with the service gateway identifyingthe at least one voice call, wherein the software, when executed by theprocessor, directs the processor to determine the circumstances underwhich the voice call is switched to the cellular voice network, toestablish an IM-based voice call to the telephone number over the IMvoice network, to include in the first call record first informationabout the IM-based voice call, to send at least a portion of the firstcall record to the switchover agent, to create a second call recordassociated with the telephone number including the at least a portion ofthe first call record and second information about the IM-based voicecall, to establish a cellular-based voice call and include informationabout the cellular-based voice call in the first call record, toassociate the cellular-based voice call with the IM-based voice call, tosend a signal to a cellular phone agent indicating that thecellular-based voice call is for switch over purpose, and to establishthe cellular-based voice call with the service gateway.
 11. The systemaccording to claim 10 wherein the telephone number is associated with awireless phone.
 12. The system according to claim 10 wherein the servicegateway comprises software which, when executed by the processor,directs the processor to connect the voice call from the call network tothe IM-based voice call.
 13. The system according to claim 11 whereinthe wireless phone comprises software which, when executed by aprocessor, directs the processor to connect to the voice call from thecall network via the IM-based voice call after the IM-based voice callis established.
 14. The system according to claim 10 wherein the servicegateway comprises software which, when executed by the processor,directs the processor to establish a cellular-based voice call to atelephone number over the cellular voice network using a cellular phonenumber during the voice call from the call network.
 15. The systemaccording to claim 14 wherein the service gateway software directs theprocessor to connect the cellular-based call over the cellular voicenetwork to the voice call from the call network.
 16. The systemaccording to claim 10, wherein the call record comprises an IM useridentity, a call reference and a cellular phone number.
 17. Anon-transient, computer readable, storage medium containing a program,which when executed by a processor causes the processor to performactions, comprising: receiving in a service gateway a voice calldestined for a telephone number, creating a first call record associatedwith the service gateway identifying the voice call, establishing overan Instant Message (IM) voice network an IM-based voice call with an IMphone agent, including in the first call record first information aboutthe IM-based voice call, connecting the voice call to the IM-based voicecall, sending at least a portion of the first call record to aswitchover agent, creating a second call record associated with thetelephone number including the at least a portion of the first callrecord and second information about the IM-based voice call,establishing a cellular-based voice call and including information aboutthe cellular-based voice call in the first call record, associating thecellular-based voice call with the IM-based voice call, sending a signalto a cellular phone agent indicating that the cellular-based voice callis for switch over purpose, and establishing the cellular-based voicecall with the service gateway.
 18. The storage medium containing aprogram according to claim 17 wherein the telephone number is associatedwith a wireless phone.
 19. The storage medium containing a programaccording to claim 17 wherein the service gateway switches the voicecall destined for the telephone number from the IM-based voice call tothe cellular-based voice call.
 20. The storage medium containing aprogram according to claim 17 wherein the switchover is based oninformation about the IM-based voice call and the cellular-based voicecall.
 21. The storage medium containing a program according to claim 20wherein the switchover is based on whether the quality of the cellularvoice call is better than IM-based voice call.
 22. The storage mediumcontaining a program according to claim 20 wherein the switchover isbased on whether the quality of the IM-based voice call is below anacceptable threshold.
 23. The storage medium containing a programaccording to claim 17 wherein the switchover is based on a useraccepting a switchover offer from the switchover agent.
 24. The storagemedium containing a program according to claim 17 comprisingestablishing the cellular-based voice call using a cellular telephonenumber wherein the cellular telephone number is different from thetelephone number.
 25. The storage medium containing a program accordingto claim 17 comprising establishing the IM-based voice call using a IMuser identity wherein the IM user identity is different from thetelephone number.
 26. The storage medium containing a program accordingto claim 18 wherein in the action of establishing over an IM voicenetwork an IM-based voice call with an IM phone agent the IM phone agentis associated with the wireless phone.
 27. The storage medium containinga program according to claim 18 wherein in the action of sending atleast a portion of the first call record to a switchover agent theswitchover agent is associated with the wireless phone.